What do the following two equations represent? $-3x-y = -1$ $x-3y = -3$
Explanation: Putting the first equation in $y = mx + b$ form gives: $-3x-y = -1$ $-y = 3x-1$ $y = -3x + 1$ Putting the second equation in $y = mx + b$ form gives: $x-3y = -3$ $-3y = -x-3$ $y = \dfrac{1}{3}x + 1$ The slopes are negative inverses of each other, so the lines are perpendicular.